Strip line device, printed wiring board mounting member, circuit board, semiconductor package, and method of forming same

ABSTRACT

Electromagnetic waves leaking from a power distribution circuit provided on a printed wiring substrate or in a semiconductor package are suppressed, and degradation of the waveform of a signal generated by a high-speed digital circuit. A strip line device comprises an elongated metal plate ( 10 ) having a valve action and coated with a dielectric film ( 20 ). A conductive layer ( 30 ) is formed to cover the valve-acting metal, with the dielectric film ( 20 ) interposed therebetween. The characteristic impedance as seen from its input terminal can be low over a wide range.

TECHNICAL FIELD

The present invention relates a technique for suppressingelectromagnetic waves leaking through a power distribution circuitprovided on a printed wiring board or a semiconductor package andpreventing degradation of the waveform of a signal excited by ahigh-speed digital circuit, and particularly to a stripline device whichis connected between a high-speed digital circuit and a powerdistribution circuit, reduces a characteristic impedance on the side ofthe power distribution circuit over a wide frequency band as viewed fromthe high-speed digital circuit to suppress the leakage ofelectromagnetic waves, and is suitable for preventing degradation of thewaveform of a signal excited by the high-speed digital circuit, acircuit board using the device, a semiconductor package, and a method offorming the stripline device.

BACKGROUND ART

In recent years, starting with mobile phones, there has been aconsiderable demand for compact and high-speed electronic devices. Thisdemand is satisfied by, e.g., increasing the speed of a clock signal inswitching power supplies and the components of digital signal processingcircuits. Accordingly, a high-frequency current increases in circuits,particularly in power supply circuits, so that an electromagneticradiation increases and signal quality degrades in a considerablemanner. Hence, there has been an increasingly vocal demand for higherperformance of devices for decoupling power.

Since high-performance digital devices include high-speed circuitsoperating at high speed and low-speed circuits operating at low speed,the spectrum of electromagnetic waves leaking into a power distributioncircuit is recently distributed over an extremely wide band of severalhundreds kHz to several tens GHz. The current of a direct-current powersupply of a semiconductor integrated circuit, which is relatively largeand is mounted on a circuit board, reaches a high level exceedingseveral tens amperes. As shown in FIG. 1, the power distribution circuitis a circuit including a power supply circuit and a power distributionwire for supplying, to another circuit, power having been supplied fromthe power supply circuit.

Leaked electromagnetic waves propagate through the power distributionwire and other circuits to the power supply circuit and cause a failureon a circuit fed with power from the power supply circuit. In general, anumber of signal wires are disposed around the power distribution wireof the board. Thus, leaked electromagnetic waves are readily coupled toa number of signal wires. The leaked electromagnetic waves having beencoupled to the signal wires degrade signal quality and propagate ashigh-frequency current through the signal wires to an external signalcable of a digital device. Then, the external signal cable acts as anantenna to radiate unwanted electromagnetic waves at high level to theair.

Further, some of the leaked electromagnetic waves propagating throughthe power distribution wire pass through the power supply circuit andpropagate through a commercial AC power supply line. The commercial ACpower supply line acts as an antenna to radiate unwanted electromagneticwaves at high level to the air. Meanwhile, the leaked electromagneticwaves propagate through the power distribution wire while repeatingreflection at some midpoint in the power distribution wire. Thus, someof the leaked electromagnetic waves also propagate through the signalwire and degrade the waveform of a signal.

As shown in FIG. 1, a drastic measure for solving the above problem isto prevent electromagnetic waves generated by circuit operations (e.g.,a switching operation of a switching element) from leaking into thepower distribution wire. In order to solve the problem, it is necessaryto considerably reduce an impedance relative to a high frequency in allfrequency bands included in electromagnetic waves when viewing the powerdistribution circuit from a circuit for generating the electromagneticwaves.

When the impedance of the power distribution circuit viewed from atransistor becomes closer and closer to 0, electromagnetic waves excitedby the transistor reflect on the entrance of the power distribution wireand do not enter the power distribution circuit.

Conventionally, capacitors are used to reduce the impedances of powerdistribution wires. As components used for electric and electromagneticdevices, capacitors have a long history and various kinds have been putinto practical use so far. At present, capacitors such as ceramiccapacitors and solid electrolytic capacitors are developed. In theceramic capacitors, a ceramic material deposited with a metal thin filmis laminated in multiple layers. In the solid electrolytic capacitors, aporous compact of a metal such as tantalum and aluminum with a valveaction is used as an anode, an oxide film is used as a dielectric, and aconducting polymer is used as a solid electrolyte.

As a solid electrolytic capacitor, the following is known: a solidelectrolytic capacitor having polypyrrole or an alkyl substitute thereofas a solid electrolyte on a dielectric oxide film (e.g., Patent Document1), or a solid electrolytic capacitor having polyaniline formed as asolid electrolyte on a dielectric oxide film and a method ofmanufacturing the same (e.g., Patent Document 2). As compared withconventional capacitors, conducting polymers higher in conductivity bytwo digits or more are used as solid electrolytes and thus thesecapacitors have a low equivalent series resistance. With the samecapacitance, these capacitors can exert effects in a high frequency areawhich is larger by two digits or more than those of the conventionalcapacitors.

However, these capacitors have two-terminal structures for acharging/discharging function, so that these capacitors rapidly increasean impedance between terminals of a high frequency area exceeding 10MHz. Thus, these capacitors have become unsuitable for the powerdistribution circuits of digital circuits. For this reason, multilayerfeedthrough capacitors and capacitor arrays for connecting a number ofsmall multilayer ceramic capacitor chips in parallel have beendeveloped. However, it has been difficult to efficiently reduce animpedance in a high frequency area exceeding 10 MHz.

To handle higher frequencies, the configurations of filters have beenalso studied. For example, a surface-mount noise filter has beenproposed which is composed of a meandering conductor and a groundconductor which are interposed between ceramic dielectric sheets (e.g.,Patent Document 3). FIG. 2 is a sectional view showing the configurationof the surface-mount noise filter composed of the meandering conductorand the ground conductor which are interposed between the ceramicdielectric sheets.

As shown in FIG. 2, the conventional surface-mount filter is configuredsuch that a first dielectric sheet 110, a second dielectric sheet 120,and a third dielectric sheet 130 are laminated. A first internalconductor 111, a meandering conductor 115, and a second internalconductor 112, which are used for transmitting a signal, are disposed onan interface between the first dielectric sheet 110 and the seconddielectric sheet 120. A ground conductor 125 is formed on an interfacebetween the second dielectric sheet 120 and the third dielectric sheet130 so as to face the meandering conductor 115.

An end of the first internal conductor 111 is connected to a firstsignal electrode 151, an end of the second internal conductor 112 isconnected to a second signal electrode 152, and the meandering conductor115 is connected between the other ends of the first internal conductor111 and the second internal conductor 112. With this configuration, itis possible to obtain a noise filter which is superior in noiseabsorbing property at high frequencies to a noise filter having acombination of a conventional inductance element and capacitanceelement.

In such a surface-mount filter, an electric signal inputted from one ofthe electrodes, e.g., the first signal electrode 115 is filtered and thefiltered electric signal is outputted to the other (second signalelectrode 152). However, in the surface-mount filter, a capacitanceformed as a distributed constant is constituted of the ground conductor125, the meandering conductor 115, and the dielectric sheets laminatedbetween the conductors. Only with the distribution capacitance, it isdifficult to efficiently reduce an impedance in a high frequency areaexceeding 10 MHz. Hence, a part of the internal conductor is used as ameandering conductor, so that a capacitance and a series inductance arecombined to enhance the effect of attenuating signals.

Further, in order to bring an impedance of a power distribution circuitcloser and closer to 0 as viewed from a switching element such as atransistor, the following has been disclosed: a technique using a powerdistribution circuit as a low impedance line (e.g., Patent Document 4)and a technique for forming a low impedance line by using a techniquefor manufacturing a solid electrolytic capacitor (e.g., Patent Document5).

A multilayer printed board disclosed in Patent Document 4 is configuredas below:

The multilayer printed board is characterized in that ground layers arelaminated respectively via insulating material layers on the upper andlower sides of a power supply layer having a power supply wire. Further,a signal layer having a signal wire is laminated via a second insulatingmaterial layer on one or both of the upper and lower ground layers. Withthis configuration, direct-current power can be supplied to circuitelements such as a semiconductor IC and an LSI mounted on a multilayerprinted board as in the case where an independent power supply of a lowimpedance is provided separately. Moreover, it is possible to suppressthe radiation of electromagnetic waves from electronic devices withoutinterfering with high-speed and high-frequency operations of the circuitelements such as an IC and an LSI mounted on the printed board.

A transmission line component disclosed in Patent Document 5 isconfigured such that a cylindrical external conductor, which is made ofa conductive material larger in diameter than an internal conductor, iscoaxially disposed via a high permittivity insulating material so as tocover a surface of the internal conductor made of a conductive material,so that a coaxial line of an extremely low characteristic impedance isformed. The component is inserted in series between a power supply lineof a printed circuit board and a power supply port of a high-speed radiofrequency circuit element such as an LSI, so that direct-current powercan be supplied as in the case where an independent power supply of alow impedance is provided separately for each high-speed radio frequencycircuit element mounted on the printed circuit board. Additionally,high-frequency power supply current generated from the high-speed radiocircuit element by a high-speed switching operation is caused to have adielectric loss in the transmission line component, so that it ispossible to suppress power supply coupling between a power supply lineand a signal line and the flow of high-frequency power supply currentfrom the power supply line of the printed circuit board to a powersupply cable in an apparatus.

[Patent Document 1]

Japanese Patent Publication No. 4-56445 (Japanese Patent Laid-Open No.60-37114)

[Patent Document 2]

Japanese Patent Laid-Open No. 3-35516

[Patent Document 3]

Japanese Patent Laid-Open No. 6-53046

[Patent Document 4]

Japanese Patent Laid-Open No. 2001-53449

[Patent Document 5]

Japanese Patent Laid-Open No. 2002-335107

Problems That the Invention is to Solve

As described above, capacitors such as ceramic capacitors and solidelectrolytic capacitors have been developed. In the ceramic capacitors,a ceramic material deposited with a metal thin film is laminated inmultiple layers. In the solid electrolytic capacitors, a porous compactof a metal such as tantalum and aluminum with a valve action is used asan anode, an oxide film is used as a dielectric, and a conductingpolymer is used as a solid electrolyte. These capacitors are used forvarious purposes as capacitors usable in a high frequency area. However,these capacitors are not considered as line devices in view of thetransmission of electromagnetic waves and have two-terminal structuressimply for obtaining the charging/discharging function. Thus, animpedance rapidly increases in a high frequency area exceeding 10 MHz.

Hence, in operations at a clock frequency exceeding several hundredsMHz, as long as the capacitors with such a function are used, it is notpossible to sufficiently reduce a characteristic presumed to appear in asignal generator circuit, that is, an internal impedance of a powersupply at a high frequency.

Although surface-mount filters are have been developed to remove noise,it is difficult to sufficiently reduce an impedance. Thus, the use ofthe surface-mount capacitor as a substitute is limited. Particularly ina high frequency area of 100 MHz or higher, a low impedance is hard toobtain.

The present invention is devised in view of the above-describedcircumstances. An object of the present invention is to provide astripline device which is mainly used as a bypass device of a noisefilter and a decoupling device and is suitable for a higher speed and ahigher frequency, a printed wiring board integrated with the striplinedevice, and a semiconductor package.

DISCLOSURE OF THE INVENTION

In order to attain the object, the invention of claim 1 is characterizedin that the invention has a metal which has a valve action, a dielectriccoating formed on a surface of the metal having the valve action, and aconductive material layer formed around the metal having the valveaction via the dielectric coating, a pair of first electrode leadingterminals is provided on both ends in the longitudinal direction of themetal to make connection to through holes of a printed wiring board anda pair of second electrode leading terminals is provided on differentpositions of the metal member to make connection to through holes of theprinted wiring board.

It is preferable to form the metal having the valve action into arectangular, a circle or oval, a ring, or a plate or foil in crosssection.

It is preferable to bend or curve both ends of a stripline device.

It is preferable for the metal having the valve action to have alongitudinal width larger than a cross sectional width.

It is preferable that the electrode leading terminal in contact with theprinted wiring board have an area larger than a cross sectional area ofthe electrode leading terminal not coming into contact with the printedwiring board.

According to a second aspect of the present invention, a striplinedevice has a metal which has a valve action, a dielectric coating formedon a surface of the metal, a conductive material layer formed around themetal via the dielectric coating, and a metal member which is disposedin contact with the conductive material layer and transmitsdirect-current power.

It is preferable that the stripline device comprise a first electrodeleading terminal for connecting an end of the metal having the valveaction and a printed wiring board, second electrode leading terminalsconnected to the printed wiring board be integrally formed on the metalmember, and

the second electrode leading terminals and the first electrode leadingterminals connected to both ends of the metal having the valve actionform four terminals.

Further, it is preferable that the first electrode leading terminal havea connecting member connected to the metal having the valve action, afirst leg member connected to a wire on the printed wiring board, and afirst body member for connecting the connecting member and the legmember,

the connecting member and the first leg member be connected almostperpendicularly to both ends in the longitudinal direction of the firstbody member, the second electrode leading terminal integrally formed onthe metal member have a second body member and a second leg member formaking connection to a wire on the printed wiring board,

the second body members be connected to an upper end of the samemounting surface of both ends in the longitudinal direction of the metalmember, and

the second leg member be connected to the body member almost in parallelwith the mounting surface.

Moreover, according to the second aspect of the present invention, it ispreferable that the first electrode leading terminal have a connectingmember connected to the metal having the valve action, a first legmember connected to a wire on the printed wiring board, and a first bodymember for connecting the connecting member and the leg member,

a member be provided to interpose the first body member between theconnecting member connected to the first body member and the first legmember on both ends in the longitudinal direction of the first bodymember and connect the connecting member and the first leg member almostperpendicularly to the first body member, and

the second electrode leading terminals have second leg members connectedto both ends in the longitudinal direction of the metal member and nearone of the long sides of the metal member almost in parallel with themounting surface, and

it is preferable that the first electrode terminal have a connectingmember connected to the metal having the valve action and a first bodymember connected to a wire on the printed wiring board,

the connecting member be connected to an end in the longitudinaldirection of the first body member almost perpendicularly to the firstbody member, and

the second electrode leading terminal have a second body memberconnected almost perpendicularly to the vicinity of one of the longsides of both ends in the longitudinal direction of the metal member.

It is preferable that the first electrode leading terminal have aconnecting member connected to the metal having the valve action and afirst body member connected to a wire on the printed wiring board,

the connecting member be connected to an end in the longitudinaldirection of the first body member almost perpendicularly to the firstbody member, and

the second electrode leading terminal have a second body memberconnected almost perpendicularly to a central area near both ends in thelongitudinal direction of a mounting surface of the metal member, and

the first electrode leading terminal and the second electrode leadingterminal be disposed almost in line with each other in the longitudinaldirection of the mounting surface.

Particularly, in the second aspect, it is preferable that the first legmember and the second leg member be larger in cross sectional area thanthe first body member and the second body member not coming into contactwith the printed wiring board.

According to the first and second aspects of the present invention, itis preferable for the conductive material layer to include a layer of aconducting polymer,

it is preferable that the conducting polymer be one or more compoundsselected from the group consisting of polypyrrole, polythiophene, andpolyaniline, or a derivative of the compounds,

it is preferable that the conductive material layer have the conductingpolymer layer disposed on the side of the dielectric coating and aconductive paste layer formed on the conducting polymer layer, and

it is preferable to fix the metal member on the conductive paste layer.

According to the first and second aspects of the present invention, itis preferable that the metal having the valve action be a metal selectedfrom the group consisting of aluminum, tantalum, and niobium, and

it is preferable that the metal having the valve action, the dielectriccoating, and the conductive material layer be molded with resin.

A third aspect of the present invention is a printed wiring boardmounting member, characterized in that the mounting member comprises alow impedance line device having a laminated structure in which adielectric coating having a dielectric loss is interposed between firstand second conductors, first electrode leading terminals which aredisposed on both ends of one of the conductors to make connection to aprinted wiring board, and second electrode leading terminals forconnecting both ends of a metal member for mounting the low impedanceline device and the printed wiring board,

the first electrode leading terminal has a connecting member connectedto the first conductor, a first leg member connected to a wire on theprinted wiring board, and a first body member for connecting theconnecting member and the leg member,

the connecting member and first leg member comprise members on both endsin the longitudinal direction of the first body member to makeconnection almost perpendicularly to the first body member,

the second electrode leading terminal has a second body member connectedto the metal member and a second leg member connected to a wire on theprinted wiring board,

the second body members are connected to an end on the same long side ofboth ends in the longitudinal direction of a mounting surface of themetal member, and

the second leg member is connected to the second body member almost inparallel with the mounting surface.

A fourth aspect of the present invention is a printed wiring boardmounting member, characterized in that the mounting member comprises alow impedance line device having a laminated structure in which adielectric coating having a dielectric loss is interposed between firstand second conductors, first electrode leading terminals which aredisposed on both ends of one of the conductors to make connection to aprinted wiring board, and second electrode leading terminals which aredisposed on both ends of a metal member for mounting the low impedanceline device to make connection to the printed wiring board,

the first electrode leading terminal has a connecting member connectedto the first conductor, a first leg member connected to a wire on theprinted wiring board, and a first body member for connecting theconnecting member and the leg member,

members are provided on both ends in the longitudinal direction of thefirst body member to interpose the first body member between theconnecting member and the first leg member and make connection almostperpendicularly to the first body member, and

the second electrode leading terminals have second leg members connectedto an end on the same long side of both ends in the longitudinaldirection of a mounting surface of the metal member almost in parallelwith the mounting surface.

A fifth aspect of the present invention is a printed wiring boardmounting member, characterized in that the mounting member comprises alow impedance line device having a laminated structure in which adielectric coating having a dielectric loss is interposed between firstand second conductors, first electrode leading terminals which aredisposed on both ends of one of the conductors to make connection to aprinted wiring board, and second electrode leading terminals which aredisposed on both ends of a metal member for mounting the low impedanceline device to make connection to the printed wiring board,

the first electrode leading terminal has a connecting member connectedto the first conductor, a first leg member connected to a wire on theprinted wiring board, and a first body member for connecting theconnecting member and the leg member,

the connecting member is connected almost perpendicularly to an end inthe longitudinal direction of the first body member, and

the second electrode leading terminals have second body membersconnected to an end on the same long side of both ends in thelongitudinal direction of a mounting surface of the metal member almostperpendicularly to the mounting surface.

A sixth aspect of the present invention is a printed wiring boardmounting member, characterized in that the mounting member comprises alow impedance line device having a laminated structure in which adielectric coating having a dielectric loss is interposed between firstand second conductors, first electrode leading terminals which aredisposed on both ends of one of the conductors to make connection to aprinted wiring board, and second electrode leading terminals which aredisposed on both ends of a metal member for mounting the low impedanceline device to make connection to the printed wiring board,

the first electrode leading terminal has a connecting member connectedto the first conductor, a first leg member connected to a wire on theprinted wiring board, and a first body member for connecting theconnecting member and the leg member,

the connecting member is connected almost perpendicularly to alongitudinal end of the first body member,

the second electrode leading terminal has a second body member connectedalmost to the center of a short side on both ends in the longitudinaldirection of a mounting surface of the metal member almostperpendicularly to the short side, and

the first electrode leading terminal and the second electrode leadingterminal are disposed almost in line with each other in the longitudinaldirection of the mounting surface.

Particularly it is preferable that the first leg member and the secondleg member in contact with the printed wiring board be larger in crosssectional area than the first body member and the second body member notcoming into contact with the printed wiring board, and

it is preferable that the low impedance line device be molded withresin.

A seventh aspect of the present invention is a circuit board having ametal which has a valve action, a dielectric coating formed on a surfaceof the metal having the valve action, a conductive material layer formedaround the metal having the valve action via the dielectric coating, anda metal member for transmitting direct-current power to be inputted,characterized in that the circuit board comprises a stripline devicehaving first and second input/output terminals on both ends of the metalhaving the valve action and both ends of the metal member, a board, anda first power supply wire and a second power supply wire formed on theboard, and

the first power supply wire and the second power supply wire areconnected to the first and second input/output terminals, respectively.

Particularly it is preferable that circuit elements for receiving powerof an equal voltage be disposed on the circuit board in an integratedmanner and an equal power be supplied by a bus bar.

An eighth aspect of the present invention is a semiconductor packagehaving a metal which has a valve action, a dielectric coating formed ona surface of the metal having the valve action, a conductive materiallayer formed around the metal having the valve action via the dielectriccoating, and a metal member for transmitting direct-current power to beinputted, characterized in that the semiconductor package comprises astripline device having first and second input/output terminals on bothends of the metal having the valve action and both ends of the metalmember, a substrate made of an insulating material, and a semiconductorchip mounted on the substrate,

the substrate has a first connector pin and a second connector pin whichare connected to the device mounted on the board,

the semiconductor chip has a first power supply wire and a second powersupply wire, and

the first and second input/output terminals are connected to theconnector pins of the substrate and the power supply wires of thesemiconductor chip, respectively.

A ninth aspect of the present invention is a method of forming astripline device, characterized by comprising the steps of:

forming a metal having a valve action,

forming a dielectric coating on a surface of the metal having the valveaction,

forming a conductive material layer around the metal having the valveaction via the dielectric coating to form a strip line,

bonding the strip line and a plurality of substrates, on which a metalmember having a second electrode leading terminal and a lead frameserving as a first electrode leading terminal are integrally formed,after performing positioning such that the conductive material layer andthe metal member are in contact with each other and the lead frame andthe metal having the valve action are in contact with each other, and

cutting the second electrode leading terminal and the lead frame fromthe substrate at a predetermined distance to complete a striplinedevice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for explaining the influence of power generated froma switching element constituting an LSI on a power distribution wiring.

FIG. 2 is a sectional view showing an example of a conventionalsurface-mount filter.

FIG. 3 is a perspective view showing an external shape of a striplinedevice according to an embodiment of the present invention.

FIG. 4 is a sectional view taken along line A-A′ of FIG. 3.

FIG. 5 is a diagram for explaining a method of measuring the capacitanceof an aluminum piece.

FIG. 6 is a sectional view showing a stripline device according to thesecond embodiment of the present invention.

FIG. 7 is a sectional view showing a stripline device according to thethird embodiment of the present invention.

FIG. 8 is a sectional view showing a stripline device according to thefourth embodiment of the present invention.

FIG. 9 is a sectional view showing a stripline device according to thefifth embodiment of the present invention.

FIG. 10 is a sectional view showing a stripline device according to thesixth embodiment of the present invention.

FIG. 11 is a sectional view showing a stripline device according to theseventh embodiment of the present invention.

FIG. 12 is a sectional view showing a stripline device according to theeighth embodiment of the present invention.

FIG. 13 is a sectional view showing a stripline device according to theninth embodiment of the present invention.

FIG. 14 is a sectional view taken along line B-B′ of FIG. 13.

FIG. 15 is a perspective view showing a configuration when the striplinedevice of the present invention is mounted on a multilayer printedwiring board.

FIG. 16 is a diagram showing a configuration when a bus bar is providedand the stripline device is mounted on the multilayer printed wiringboard.

FIG. 17 is a sectional view showing the multilayer printed wiring boardshown in FIG. 16.

FIG. 18 is a structural diagram showing the configuration of the busbar.

FIG. 19 is a diagram showing a first mode of an electrode leadingterminal formed when the stripline device is mounted on the multilayerprinted wiring board.

FIG. 20 is a side view showing the stripline device of FIG. 19 along thelength direction and the width direction of the device.

FIG. 21 is a diagram showing an external shape of the stripline deviceof FIG. 19 that has been molded with resin.

FIG. 22 is a diagram showing a second mode of the electrode leadingterminal formed when the stripline device is mounted on the multilayerprinted wiring board.

FIG. 23 is a side view showing the stripline device of FIG. 22 along thelength direction and the width direction of the device.

FIG. 24 is a diagram showing a third mode of the electrode leadingterminal formed when the stripline device is mounted on the multilayerprinted wiring board.

FIG. 25 is a side view showing the stripline device of FIG. 24 along thelength direction and the width direction of the device.

FIG. 26 is a diagram showing a fourth mode of the electrode leadingterminal formed when the stripline device is mounted on the multilayerprinted wiring board.

FIG. 27 is a side view showing the stripline device of FIG. 26 along thelength direction and the width direction of the device.

FIG. 28 is a diagram showing that a plurality of metal plates and leadframes are continuously connected on a substrate to form striplinedevices.

FIG. 29 is a diagram showing an external shape when the striplinedevices are bonded on the substrate of FIG. 28 and are molded withresin.

FIG. 30 is a diagram showing an external shape of the stripline devicein which the metal plate and the lead frame are connected to each otherand legs are cut at a predetermined length.

FIG. 31 is a side view showing a configuration when the stripline deviceof FIG. 30 is viewed along the length direction and the width directionof the device.

FIG. 32 is a diagram showing the configuration of a stripline devicecomprising a plurality of second electrode leading terminals.

FIG. 33 is a diagram showing the configuration of a stripline devicecomprising a plurality of first and second electrode leading terminals.

FIG. 34 is a diagram showing the configuration of a stripline devicehaving the first electrode leading terminals drawn in the widthdirection.

FIG. 35 is a diagram showing the configuration of a stripline devicehaving the first and second electrode leading terminals drawn in thewidth direction.

FIG. 36 is an equivalent circuit diagram for calculating a reflectioncoefficient Γ and a transmission coefficient T on a line.

FIG. 37 is a diagram showing the relationship between a frequency and atransmittance of a decoupling device.

FIG. 38 is a perspective view showing that the stripline device of thepresent invention is mounted on a semiconductor package.

In the drawings, reference numeral 1 denotes a stripline device.Reference numeral 2 (2A, 2B) denotes first electrode leading terminals(terminals). Reference numeral 3 (3A, 3B) denotes second electrodeleading terminals (terminals). Reference numeral 10 denotes a valvemetal. Reference numerals 11 and 12 denote first electrode leadingterminals. Reference numeral 20 denotes a dielectric coating. Referencenumeral 30 denotes a conductive material layer. Reference numeral 31denotes a conducting polymer layer. Reference numeral 32 denotes aconductive carbon paste layer. Reference numeral 33 denotes silverpaste. Reference numeral 40 denotes a metal plate. Reference numerals 41and 42 denote second electrode leading terminals. Reference numeral 60denotes an insulating material. Reference numeral 70 denotes a printedwiring board. Reference numerals 71 a and 71 b denote positive powerwires. Reference numerals 74 a and 74 b denote negative power wires.Reference numeral 79 denotes an insulating layer. Reference numeral 80denotes a semiconductor package. Reference numerals 81 a and 78 b denotepositive power wires. Reference numerals 84 a and 84 b denote negativepower wires. Reference numeral 85 denotes a semiconductor chip.Reference numeral 86 denotes a connector pin. Reference numeral 89denotes an insulating layer. Reference numeral 110 denotes a firstdielectric sheet. Reference numeral 111 denotes a first internalconductor. Reference numeral 112 denotes a second internal conductor.Reference numeral 115 denotes a meandering conductor. Reference numeral120 denotes a second dielectric sheet. Reference numerals 123 and 124denote intervals of electrical insulation. Reference numeral 125 denotesa ground conductor. Reference numeral 130 denotes a third dielectricsheet. Reference numeral 151 denotes a first signal electrode. Referencenumeral 152 denotes a second signal electrode.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments will be described below in accordance with theaccompanying drawings. However, the present invention is not limited tothe embodiments discussed below.

First Embodiment

FIG. 3 is a perspective view showing an external shape of a striplinedevice according to an embodiment of the present invention.

FIG. 4 is a sectional view showing the stripline device taken along lineA-A′ of FIG. 3.

As shown in FIGS. 3 and 4, the stripline device of the present inventioncomprises a metal (hereinafter, referred to as a valve metal) 10 whichhas a dielectric coating 20 on its surfaces and is shaped like a longplate with a valve action, and a conductive material layer 30 with whichthe valve metal 10 is coated via the dielectric coating 20. In thisconfiguration, as shown in FIG. 3, the stripline device 1 comprises thevalve metal 10 which is almost flat. Both ends in the longitudinaldirection of the valve metal 10 are almost in line with the ends of thestripline device 1.

For example, the valve metal 10 is made of aluminum. In the example ofFIG. 3, the valve metal 10 is a rectangle which is, e.g., 110 μm inthickness, 30 mm in length, and 10 mm in width. The shape of the valvemetal 10 in cross section is not limited to a rectangle and may be anoval or a ring. The surfaces of the valve metal 10, that is, the frontside, back side, and end faces of the valve metal 10 are increased insurface area by about 200 times by electrolytic etching in anelectrolytic solution. Spongy holes are formed on the valve metal 10.

The conductive material layer 30 is formed so as to cover the valvemetal 10 via the dielectric coating 20 except for both ends of the valvemetal 10. The material and so on of the conductive material layer 30 arenot particularly limited as long as the material is conductive. Forexample, various metals, semiconductors such as manganese dioxide andindium oxide, or organics conductors such as a charge-transfer complexof tetracyanoquinodimethane and tetrathiafulvalene are available.

Particularly, for the conductive material layer 30, conducting polymersare preferable, examples of which include polypyrrole, polythiophene,polyethylene dioxythiophene, polyaniline, polypheylene, polyfuran,polythiazyl, polyphenylenevinylene, polyacetylene, and polyazulene.Particularly, polypyrrole, polythiophene, polyaniline, and derivativesthereof are preferable in view of stability. In the present invention,derivatives of polypyrrole, polythiophene, and polyaniline include,e.g., derivatives obtained by adding various substituents to thesecompounds and derivatives obtained by copolymerization with other highpolymers.

In the present invention, these conducting polymers are generally usedafter being combined with a dopant composed of an electron-donating orelectron-withdrawing compound. In the present invention, a dopantcombined with the conducting polymers is not particularly limited. Aconventionally known dopant is used for the conducting polymers. Forexample, such a dopant includes a dopant acting as a halogen compound ofiodine, chlorine, anion perchlorate or the like, a dopant acting as aLewis acid of an aromatic sulfonic acid compound or the like, or adopant acting as a Lewis base such as lithium and tetraethylammonium.

To further reduce an impedance, a metal plate 40, which is made ofcopper, silver, gold, aluminum, or other materials with a low electricresistance, is disposed so as to face either or both surfaces of thevalve metal. The conductive material layer 30 is interposed between themetal plate 40 and the valve metal. In the present embodiment of FIG. 3,the metal plate 40 is disposed in contact with one side of a rectangularparallelepiped. The metal plate 40 may be disposed so as to surround (orpartially surround) the rectangular parallelepiped. Since the conductivematerial layer 30 is an extremely thin film, the metal plate is disposedoutside the conductive material layer 30 so as to surround theconductive material layer 30 in order to obtain mechanical strength andreduce an electric resistance.

In the present invention, regarding these conducting polymersconstituting the conductive material layer 30, a forming method is notparticularly limited. The conducting polymers can be formed as follows:a solution of conducting polymers is developed and evaporated on thesurfaces of the valve metal 10 where the dielectric coating 20 is formed(i.e., on the dielectric coating), a monomer and an oligomer, which formthe conducting polymers, and a polymerization catalyst are introduced topolymerize conducting polymers directly on the surfaces of the valvemetal, or a high-polymer layer composed of an intermediate of conductingpolymers is formed and converted into conducting polymers.

Further, a connection to a wiring board and an electronic circuit boardmay be made by direct mounting on the board. Alternatively, an electrodemay be drawn and sealed with a resin, a metallic case, and so on. As anexample of a configuration having electrode leading terminals, in thepresent embodiment, first electrode leading terminals 2A and 2B areprovided on both ends in the longitudinal direction of the valve metal10, and second electrode leading terminals 3A and 3B are provided onboth ends in the longitudinal direction of the metal plate 40. Forexample, the first electrode leading terminals 2 may be formed byprotruding the valve metal 10 to both sides or may be attached bywelding and crimping. Similarly, the second electrode leading terminals3A and 3B may be formed by protruding the metal plate 40 to both sidesor may be attached by welding and crimping. The shape of the electrodeleading terminal is determined according to a pattern of mounting on aprinted wiring board or the like.

As shown in FIG. 1, the terminals 2A and 3A are a terminal pair forreceiving direct-current power fed from a power supply circuit, and theterminals 2B and 3B are a terminal pair for feeding direct-current powerto an LSI.

Moreover, the dielectric coating 20 is made of a material for forming aline capacitance extremely larger than a line inductance formed betweenthe first electrode leading terminals 2A and 2B and the second electrodeleading terminals 3A and 3B, so that a line impedance has an extremelysmall value. Hence, the stripline device of FIG. 3 according to theembodiment of the present invention acts so as to almost totally reflecthigh frequency electromagnetic waves of signal components, which aregenerated by switching and so on of a transistor in an LSI circuit, andunwanted electromagnetic waves entering from the power supply circuit tothe LSI.

In the embodiment of the present invention, the characteristics of thestripline device as viewed from the terminals 2A and 3A are completelysimilar to characteristics viewed from the terminals 2B and 3B. Hence,also when the direct-current power is received by the terminals 2B and3B, the action of the stripline device is similar to the above.

In the present invention, the kind of the valve metal is notparticularly limited. Metals for forming surface coatings that includetantalum, aluminum, niobium, titanium, zirconium, silicon, and magnesiumare available as the valve metal 10. These metals are used in the formof rolled foil, impalpable powder sintered compact, and so on.Particularly a metal selected from the group consisting of tantalum,aluminum, and niobium is preferably used as the valve metal 10.

Further, the method of forming the dielectric coating 20 on the surfacesof the valve metal is not particularly limited. For example, thedielectric coating 20 may be formed by electrolytic formation using anelectrolytic solution or formed by using a proper oxidizer.Alternatively, an oxide film formed by air oxidation is directly used asthe dielectric coating 20 of the present invention. However, thedielectric coating is generally formed by electrolytic formation.

The shape of the valve metal 10 is not particularly limited. In view ofa calculation of a characteristic impedance and working, a planar shape(rectangular in cross section perpendicular to the longitudinaldirection of the valve metal) is preferable but a curved shape and apartially bent shape may be also used. A columnar or cylindrical shapeis also applicable.

The surfaces of the valve metal 10 can be made larger in the presentinvention. A valve metal with larger surfaces includes an impalpablepowder sintered compact formed into a plate and etching foil having beensubjected to electrolytic etching in an electrolytic solution.

As described above, in the present invention, the conductive materiallayer 30 is preferably composed of conducting polymers. The followingconfiguration may be applicable: a layer in contact with the dielectriccoating 20 is composed of conducting polymers and another kind ofconductive material layer is formed on the layer of conducting polymers.The solid electrolyte of the conductive material and the metal plate canbe in contact with each other as they are or can be connected to eachother using conductive carbon paste and silver paste.

For example, the conductive material layer 30 may have a three-layerstructure of a conductive polymer layer directly coming into contactwith the dielectric coating 20, conductive carbon paste disposed on theconductive polymer layer, and silver paste disposed on the conductivecarbon paste. The metal plate is mounted by the silver paste.

The stripline device of the present embodiment is constituted of thevalve metal 10 having the dielectric coating 20, the conductive materiallayer 30 disposed around the valve metal 10 via the dielectric coating20, the pair of electrode leading terminals 2A and 2B disposed ondifferent positions of the valve metal 10, and the pair of electrodeleading terminals 3A and 3B disposed on different positions of theconductive material layer. This configuration increases an apparentdielectric loss and thus the characteristic impedance of the striplinedevice can be sufficiently reduced, thereby preventing anelectromagnetic wave generated from a noise source from entering a powerdistribution circuit.

The following will specifically describe an example of the manufacturingof the stripline device according to the first embodiment. The presentinvention is not limited to the manufacturing procedure discussed below.

In the stripline device shown in FIGS. 3 and 4, aluminum foil was usedas the valve metal 10. The aluminum foil was increased in surface areaby about 200 times by etching and had a thickness of 110 μm. Thealuminum foil was 10 mm in width and 30 mm in length. On both ends ofthe aluminum foil (valve metal 10), a mask (not shown) was formed usingfluorocarbon polymers of hexafluoropropylene. Then, the aluminum foilwas anodized at 10 V in an aqueous solution of 5 mass % ammonium borateand was cleaned and dried, so that the aluminum foil was obtained whichhad the dielectric coating 20 composed of a metal oxide coating. Thefoil was dipped into a sulfuric acid solution of 0.05 mol/L and acapacitance of about 380 μF was measured. As shown in FIG. 5, thecapacitance is measured while the foil is dipped into the sulfuric acidsolution. The sulfuric acid solution has a high electric conductivityand soaks into the gaps of the dielectric coating and thus it ispossible to accurately measure a capacitance proportionate to an area ofthe dielectric coating. In this case, although the low reaction velocityof the sulfuric acid solution seems to be a concern, the sulfuric acidsolution has a low measuring frequency of about 120 Hz and thus thereaction velocity causes no problem. Further, the solution is notlimited to the sulfuric acid solution and thus any solution isapplicable as long as the solution possesses conductivity.

Subsequently, in a glass container, an aqueous solution was preparedwhich contained 10 mass % p-toluenesulfonic acid and 5 mass % aniline,the valve metal 10 having the dielectric coating 20 and the mask thereonwas dipped into the aqueous solution and then was pulled out. In air ofroom temperature, the valve metal 10 was dried for 30 minutes at roomtemperature. Then, the valve metal 10 was dipped into an aqueoussolution containing 10 mass % ammonium peroxodisulfate and 10 mass %p-toluenesulfonic acid, pulled out, and left in the air for 20 minutesto polymerize aniline.

Thereafter, the valve metal 10 was cleaned with water and methanol anddried in an atmosphere of 80° C. These operations were repeated fourtimes. The conductive carbon paste and silver paste were sequentiallyapplied to complete the conductive material layer 30, and the metalplate 40 composed of copper foil of about 100 μm was fixed to theconductive material layer 30 with the silver paste. Then, both ends ofthe valve metal 10 were dipped into tetrahydrofuran, andhexafluoropropylene acting as a resin constituting the mask wasdissolved and removed.

Second Embodiment

Referring to FIG. 6, the second embodiment of the present invention willbe discussed below. The configuration of a stripline device of thepresent embodiment is different from that of the stripline device of thefirst embodiment in that a valve metal 10 is almost shaped like a squarein cross section. Other configurations of the stripline device of thepresent embodiment are similar to those of the stripline device of thefirst embodiment.

Third Embodiment

Referring to FIG. 7, the third embodiment of the present invention willbe discussed below. The configuration of a stripline device of thepresent embodiment is different from that of the stripline device of thethird embodiment in that a valve metal 10 is almost shaped like a circleor an oval in cross section. Other configurations of the striplinedevice of the present embodiment are similar to those of the striplinedevice of the first embodiment.

Fourth Embodiment

Referring to FIG. 8, the fourth embodiment of the present invention willbe discussed below. The configuration of a stripline device of thepresent embodiment is different from that of the stripline device of thefirst embodiment in that a valve metal 10 is almost shaped like a ringin cross section. That is, the cylindrical valve metal 10 is used. Otherconfigurations of the stripline device of the present embodiment aresimilar to those of the stripline device of the first embodiment.

Fifth Embodiment

Referring to FIG. 9, the fifth embodiment of the present invention willbe discussed below. The configuration of a stripline device of thepresent embodiment is different from that of the stripline device of thefirst embodiment in that a valve metal 10 has a longitudinal dimension Lwhich is larger than a cross-sectional dimension H by four times ormore. That is, since the length is larger than the width in crosssection, the valve metal 10 can act as a line. As the valve metal 10,two types of stripline devices were formed using metals which were 16 mmand 32 mm in length and 1.8 mm in width. The conductive material layer30 was composed of polythiophene, carbon paste, and silver paste. Thedielectric coating 20 was formed at a formation voltage of 8 V.

Both ends of the two kinds of stripline devices obtained thus wereconnected to a network analyzer and a power transmission property S21was measured. An impedance value was determined from values of a realpart and an imaginary part without consideration of an internal loss.The type with a length of 16 mm had an impedance value of 0.2 mΩ to 0.8mΩ, which was somewhat even in a frequency area of 20 MHz to 200 MHz.The impedance value was 10 mΩ or lower even in a frequency area of 1 MHzto 1 GHz. Meanwhile, the type with a length of 32 mm had a morepreferable result. The impedance value was around 0.1 mΩ, which issomewhat even in a frequency area of 7 MHz to 150 MHz. The impedancevalue was 10 mΩ or lower even in a frequency area of 2 MHz to 1 GHz.

Consequently, it was found that both types are lower in impedance by twoto three digits over several kHz to several GHz as compared with a 0.1μF multilayer chip ceramic capacitor, which is the most common highfrequency capacitor. In this way, it is understood that as compared withconventional capacitors, the stripline device according to theembodiment of the present invention has an extremely excellent impedancecharacteristic particularly for advanced digital devices.

Sixth Embodiment

Referring to FIG. 10, the sixth embodiment of the present invention willbe discussed below. A stripline device of the present embodiment isconfigured such that electrode leading terminals 11 and 12 in a pair,which is shaped so as to be mounted in through holes of a printed wiringboard, are provided on both ends in the longitudinal direction of avalve metal 10, and electrode leading terminals 41 and 42 in a pair,which is shaped so as to be mounted in the through holes of the printedwiring board, are provided on different positions of a metal plate 40.This configuration can obtain the stripline device suitable for mountingon the printed wiring board.

Seventh Embodiment

Referring to FIG. 11, the seventh embodiment of the present inventionwill be discussed below. A stripline device of the present embodiment isconfigured such that electrode leading terminals 11, 12, 41, and 42 inthe form of the letter L suitable for surface mounting are provided onboth ends in the longitudinal direction of a valve metal 10. If surfacemounting is not necessary, the shapes of the electrode leading terminalsare not limited to letter L. Straight shapes which are polygonal,semicircular, and circular in cross section are also applicable.

Eighth Embodiment

Referring to FIG. 12, the eighth embodiment of the present inventionwill be discussed below. A stripline device of the present embodiment isdifferent from that of the first embodiment in that the conductivematerial layer 30 of FIG. 4 is constituted of a layer 31 of conductingpolymers, a conductive carbon paste layer 32, and a silver paste layer33. Other configurations of the stripline device of the presentembodiment are similar to those of the stripline device of the firstembodiment.

Ninth Embodiment

The ninth embodiment of the present invention will be discussed below. Astripline device of the present embodiment is different from that of theeighth embodiment in that the layer 31 of conducting polymers shown inFIG. 12 is composed of one or more compounds selected from the groupconsisting of polypyrrole, polythiophene, and polyaniline, or aderivative of the compounds. Other configurations of the striplinedevice of the present embodiment are similar to those of the striplinedevice of the eighth embodiment.

Tenth Embodiment

The tenth embodiment of the present invention will be discussed below. Astripline device of the present embodiment is different from those ofthe eighth and ninth embodiments in that the stripline device isconstituted of a conductive paste layer instead of the conductive carbonpaste layer 32 and the silver paste layer 33. Other configurations ofthe stripline device of the present embodiment are similar to those ofthe stripline devices of the eighth and ninth embodiments.

Eleventh Embodiment

The eleventh embodiment of the present invention will be discussedbelow. A stripline device of the present embodiment is different fromthat of the tenth embodiment in that a metal plate 40 is fixed on theconductive paste layer of the stripline device of the tenth embodiment.Other configurations of the stripline device of the present embodimentare similar to those of the stripline device of the tenth embodiment.

Twelfth Embodiment

The twelfth embodiment of the present invention will be discussed below.A stripline device of the present embodiment is different from those ofthe first to eleventh embodiments in that a valve metal 10 is made of ametal selected from the group consisting of aluminum, tantalum, andniobium. Other configurations of the stripline device of the presentembodiment are similar to those of the stripline devices of the first toeleventh embodiments.

Thirteenth Embodiment

Referring to FIGS. 13 and 14, the thirteenth embodiment of the presentinvention will be discussed below. As shown in FIG. 14, a striplinedevice of the present embodiment has a dielectric coating 20 formed soas to sandwich a valve metal 10 and a conductive material layer 30formed so as to sandwich the dielectric coating 20. A metal plate 40 isbonded to one surface of a laminated body in which the valve metal 10,the dielectric coating 20, and the conductive material layer 30 arelaminated in the above order. Further, an insulating material 60 isdisposed on both ends of the front and back sides of the valve metal 10and surrounds both ends of the dielectric coating 20 and the conductivematerial layer 30. First electrode leading terminals 11 and 12 areprovided outside the ends having the insulating material on the valvemetal 10. Second electrode leading terminals 41 and 42 are provided onthe opposite surface of the metal plate 40 from the surface having thevalve metal 10, the dielectric coating 20, and the conductive materiallayer 30.

The stripline device of the present embodiment, in which the valve metal10, the dielectric coating 20, and the conductive material layer 30 arelaminated thus on the metal plate 40, is bent or curved in the samedirection from a major surface in the vicinity of both ends of thedevice. When a member is bent or curved thus in a plane along the samedirection, fabrication can be readily performed by dipping and thestripline device can be shortened in the longitudinal direction, so thatother components can be avoided during mounting. Moreover, in thepresent embodiment, the stripline device is bent or curved in a planeperpendicular to a mounting substrate surface for mounting the striplinedevice. The device may be bent or curved vertically with respect to asurface in parallel with the mounting substrate surface.

Referring to FIG. 15, the following will discuss a circuit configurationfor mounting the stripline devices of the first to thirteenthembodiments on a multilayer printed wiring board.

A circuit board shown in FIG. 15 comprises a multilayer printed board303, the stripline device mounted on a surface of the multilayer printedboard 303, power supply wires 301 a and 301 b connected respectively toanode leading terminals 11 and 12 (not shown) of the stripline device,and ground wires 302 a and 302 b connected respectively to cathodeleading terminals 41 and 42 (not shown) of the stripline device. Thepower supply wires 301 a and 301 b and the ground wires 302 a and 302 bare each formed on the multilayer printed board 303 by using a materialsuch as copper of high electric conductivity.

A number of circuit components (not shown) are mounted on the multilayerprinted board 303. High frequency noise from the circuit components issuperimposed on the power supply wires 301 a and 301 b and the groundwires 302 a and 302 b, propagates through these wires, and causescircuit elements to malfunction. By filtering the noise in the striplinedevice, a malfunction caused by high frequency noise is less likely tooccur on the circuit board of FIG. 15, thereby achieving stable circuitoperations at high frequencies.

Further, when a number of circuit components are mounted on the circuitboard, the circuit components are disposed close to each other, so thata noise source and the circuit components affected by the noise sourceare disposed close to each other. Also in this case, the striplinedevice inserted into the power supply wires and the ground wiresefficiently filters noise superimposed on the power supply wires and theground wires. Thus, the circuit board using the stripline device of thepresent invention can achieve high-density packaging on the circuitboard operating at high frequencies.

As shown in FIG. 16, the multilayer printed wiring board having thestripline device may supply power to each circuit element by using a busbar. When a number of signal pins are disposed immediately under an LSIto be mounted or no pin is present in a central area of the board,receiving pads are provided to connect the bus bar to the board. In theembodiment of FIG. 16, for example, circuit elements are mounted on theboard so as to correspond to supplied voltages such as 3.3 V, 2.5 V, and1.8 V and power is supplied to the board by the bus bar. Besides,printed wiring boards using bus bars may be laminated as shown in FIG.17. Alternatively, circuit elements for supplying different powers maybe mounted on a single board and bus bars may be provided to supply thecorresponding powers.

The bus bars in layers are fixed on an apparatus via an insulator, and aframe ground connection cable connects a frame ground layer and a bodyframe ground of the bus bar. FIG. 18 is a perspective view showing anexample of the bus bar. In FIG. 18, reference numeral 700 denotes thebus bar, reference numeral 701 denotes a bus bar fixing vinyl band,reference numeral 702 denotes a bus bar support (supporting portion),reference numeral 703 denotes an apparatus body ground frame, andreference numeral 704 denotes the frame ground connection cable. Thatis, the bus bar 700 is fixed on the bus bar support 702 by using the busbar fixing vinyl band 701, which is an insulator, and the frame groundconnection cable 704 connects the frame ground layer of the bus bar 700and the body frame ground 703.

In the above description, a wire paired with the power supply wire isthe ground wire. A negative power supply wire may be paired with thepower supply wire. Further, in the above description, the striplinedevice is mounted on the surface of the multilayer printed board 303.The same effect can be obtained by mounting the stripline device of thepresent invention on an internal board surface of a multilayer boardconstituting the multilayer printed board 303.

A structure for mounting the stripline device on the multilayer printedwiring board 303 will be further discussed below. In the presentembodiment, as shown in FIG. 19, the stripline device 1 is mounted onthe metal plate 40, and the stripline device and the multilayer wiringprinted board 303 are electrically connected to each other by a leadframe 500, which acts as the first electrode leading terminal forconnecting the valve metal 10 and the wire on the laminated printedboard 303, and a second electrode leading terminal 520 provided on themetal plate 40.

The following will specifically describe the shapes of the first andsecond electrode leading terminals and the mounting positions thereof.

First, in a first mode of the electrode leading terminal, the lead frame500 for electrically connecting the valve metal 10 and the multilayerprinted wiring board 303 has, as shown in FIG. 19, a joint 501 formaking connection to the valve metal 10, a first body 502 serving as theleg of the lead frame, and a first leg 503 for making connection to thewires on the multilayer printed wiring board. On both ends in thelongitudinal direction of the first body 502, the joint 501 and thefirst leg 503 are mounted almost perpendicularly to the first body 502so as to have opposite surfaces from each other with respect to thefirst body 502. Moreover, the metal plate 40 has the second electrodeleading terminals 520 each of which is constituted of a second body 521connected to a body 510 for mounting the stripline device and a secondleg 522 connected to the wires on the multilayer printed wiring board.The pair of second bodies 521 connected to the body 510 of the metalplate 40 is disposed on both ends in the longitudinal direction of themetal plate 40 and disposed on the same long side of the top surface ofthe body 510 for mounting the stripline device. The second body 521 isnot connected perpendicularly to the metal plate 40 but is mounted so asto be separated from the vertical direction to the longitudinaldirection of the metal plate 40 with distance from the joint of themetal plate 40. That is, when the metal plate 40 is viewed as shown inFIG. 19 from the short side of the metal plate ((1) direction in FIG.19), the metal plate 40 is mounted so as to be shaped like “

” by the pair of second bodies 521 as shown in FIG. 20. The second leg522 is mounted on the second body 522 in parallel with the metal plate40.

The stripline device is placed and bonded onto the metal plate 40configured thus, the lead frame is bonded to the valve metal 10 on theother end in the longitudinal direction of the metal plate. The otherend does not have the electrode leading terminals of the metal plate 40.The stripline device is mounted on the metal plate, and the lead frames500 and the second electrode leading terminals 520 provided on the endsof the metal plate constitute the stripline device of a four-terminalstructure. As shown in FIG. 21, the stripline device is molded withresin and is disposed on the printed wiring board. A diagonally shadedpart shown in FIG. 21 indicates a molded part. The joints of the legs tobe connected to the printed wiring board are all exposed from the bottomof a molded package. Further, the joint serving as the end of the leghas a larger area, that is, an area of the electrode leading terminal incontact with the printed wiring board is larger than a cross-sectionalarea of the electrode leading terminal not coming into contact with theprinted wiring board. Thus, a contact area between the printed wiringboard and the electrode leading terminal is increased, therebypreferably keeping an electrical contact. Moreover, it is possible toobtain preferred electrical characteristics (Ohmic characteristics)after a process such as solder reflow. When the stripline device havingthe electrode leading terminal is pressed from above to the printedwiring board, the diagonally provided legs reduce a stress. FIG. 20 (A)is a side view showing the stripline device viewed from (1) direction ofFIG. 19. FIG. 20(B) is a side view showing the stripline device viewedfrom (2) direction of FIG. 19. In the first embodiment, the legs 503 and522 of the first electrode leading terminal 500 and the second electrodeleading terminal 520 are widened to the outside. The legs may benarrowed to the inside (in the same direction as the first joint 501).With this configuration, it is possible to improve the packing densityof devices on a circuit board.

In a second mode of the electrode leading terminal, as shown in FIG.22(A), the second legs 522 of the second electrode leading terminal 520to be mounted on the metal plate 40 are directly connected to the body510 of the metal plate 40. The second legs 522 are arranged in parallelalong the longitudinal direction of the mounting surface of the metalplate 40 for mounting the stripline device. In the first embodiment, thesecond electrode leading terminals 520 are diagonally widened to theoutside, whereas the second legs 522 are directly connected to the metalplate 40 in the present embodiment, so that a width to the outside isreduced and a packaging density is increased. Further, in the presentembodiment, the legs to be in contact with the wires on the printedwiring board are disposed immediately under the metal plate 40 as muchas possible, thereby improving the packaging density of a package. FIG.23(A) is a side view showing the stripline device which has been moldedin the state of FIG. 22(B) and is viewed in (1) direction of FIG. 22(B).FIG. 23(B) is a side view showing the stripline device which has beenmolded in the state of FIG. 22(B) and is viewed in (2) direction of FIG.22(B). As shown in FIG. 23, in the present embodiment, the bottom of theleg is as high as the bottom of the mold or slightly higher (longer)than the mold, so that the design almost reaches the limit of the heightdirection. That is, the structure is made in consideration of a smallerthickness.

A third mode of the electrode leading terminal will be discussed below.In the third mode, as shown in FIG. 24(A), the first bodies 502 and thesecond bodies 521 are mounted almost perpendicularly to the joints 501and the metal plate 40. Further, the third mode does not have the legs503 and 522 provided in the first mode of FIG. 19. This shapefacilitates the formation of components and further reduces the area ofthe metal plate and the lead frame. Since the legs are removed, a widthto the outside is reduced and a packaging density is increased. Further,in the present embodiment, the legs to be in contact with the wires onthe printed wiring board are disposed immediately under the metal plate40 as much as possible, thereby improving the packaging density of apackage. FIG. 25(A) is a side view showing the stripline device whichhas been molded in the state of FIG. 24(B) and is viewed in (1)direction of FIG. 24(B). FIG. 25(B) is a side view showing the striplinedevice which has been molded in the state of FIG. 24(B) and is viewed in(2) direction of FIG. 24(B). As shown in FIG. 25, the bottom of the legis as high as the bottom of the mold or slightly higher (longer) thanthe mold, so that the design almost reaches the limit of the heightdirection. That is, the structure is made in consideration of a smallerthickness.

A fourth mode of the electrode leading terminal will be discussed below.In the fourth mode, as shown in FIG. 26(A), the second body 521 of thesecond electrode leading terminal to be mounted on the metal plate 40has legs disposed on both ends in the longitudinal direction of themetal plate and almost at the center of a short side of the mountingsurface for mounting the stripline device. This mode can achieve acompact four-terminal stripline device with a small width. In this way,in the present embodiment, even when there is almost no area formounting circuit elements on the board, an SIP (Single Inline Package)structure in which the stripline device is mounted so as to bevertically raised, thereby achieving high-density packaging. FIG. 27(A)is a side view showing the stripline device which has been molded in thestate of FIG. 26(B) and is viewed in (1) direction of FIG. 26(B). FIG.27(B) is a side view showing the stripline device which has been moldedin the state of FIG. 26(B) and is viewed in (2) direction of FIG. 26(B).

The metal plate 40 and the lead frame, which are used for mounting thestripline device on the multilayer printed wiring board, are fabricatedin steps discussed below, thereby simplifying the manufacturing process.

As shown in FIG. 28, the metal plate is connected to the substrate bythe legs disposed on both ends of the metal plate. As shown in FIG. 28,a plurality of metal plates are connected to the substrate. Moreover, onboth ends in the longitudinal direction of the metal plate, the leadframes are disposed at regular intervals from the ends.

As shown in FIG. 29, the stripline device is bonded to the metal platemounted on the substrate and the bonded stripline device is molded withresin. Then, the legs of the molded stripline device are cut at apredetermined length from the substrate, so that the stripline device ofFIG. 30 is completed. After cutting, resin burrs are removed which havestuck to the surfaces of the electrode leading terminals 500 and 520 orgaps between the electrode leading terminals 500 and 520. A process ofassembling semiconductors is applicable to these steps. In this way, thestripline devices are bonded to the substrate to which two or moregroups of the metal plate 40 and the lead frame have been connected, andthe legs of the electrode leading terminals are cut. Thus, it ispossible to simplify the manufacturing process of the stripline deviceand increase mass productivity. FIG. 31(A) is a side view showing thestripline device which has been molded in the state of FIG. 30 and isviewed in (1) direction of FIG. 30. FIG. 31(B) is a side view showingthe stripline device which has been molded in the state of FIG. 30 andis viewed in (2) direction of FIG. 30.

The above explanation described an example in which the first and secondelectrode leading terminals are each disposed on both ends of thestripline device. The two or more electrode leading terminals 500 and520 may be provided on both ends of the stripline device. For example,as shown in FIG. 32, the electrode leading terminals 500 may be providedrespectively on both ends in the longitudinal direction of the valvemetal, and the second bodies 521 of the second electrode leadingterminals may be provided on both ends in the length and widthdirections (i.e., four corners) of the metal plate 40.

Further, as shown in FIG. 33, the second bodies 521 of the secondelectrode leading terminals may be provided on the four corners of themetal plate 40, and the electrode leading terminals 500 may be providedon both ends of the length and width directions of the metal plate whichconstitutes the stripline device 1.

As shown in FIGS. 34 and 35, when the two or more electrode leadingterminals are provided, the electrode leading terminals may be disposedso as to protrude in the cross direction (width direction) of thestripline device. The electrode leading terminals are disposed in thecross direction of the stripline device, thereby improving a packagingstrength for the board. The above explanation described some structuresin which the two electrode leading terminals are disposed on the ends ofthe stripline device. Needless to say, three or more electrode leadingterminals may be disposed.

Further, the above explanation described the examples in which lines inthe stripline device are mounted in parallel with the board. By changingthe shapes of the first and second electrode leading terminals 500 and520, the present embodiment is also applicable to a configuration wherelines in the stripline device are mounted perpendicularly to the board(that is, vertically mounted).

Besides, the above explanation described the configuration where thestripline devices of the first to thirteenth embodiments are mounted onthe metal plate 40 and then is mounted on the printed wiring board 303.The stripline device to be mounted is not limited to the above as longas the stripline device is a low-impedance stripline devicecharacterized as below:

(1) A length sufficiently considered to be a line as viewed fromelectromagnetic waves in a frequency band to be subjected to decoupling(a part permitting the passage of electromagnetic waves preferably has asubstantial length (=an effective line length) which is equal to orlarger than a quarter of the wavelength of an electromagnetic wave at atarget frequency).

(2) A sufficiently low impedance of a line device relative to a highfrequency as viewed from a circuit for generating electromagnetic waves.

Regarding (1), it can be said that a transmission line generally has aconstant characteristic impedance over a wide frequency range. Formula(1) indicates a characteristic impedance Zy of the stripline device. Inan area where a resistance R and a conductance G are negligible, thecharacteristic impedance is determined by L and C regardless of afrequency. Thus, by designing a transmission line having a lowinductance L per unit length and a large capacitance C per unit length,it is possible to achieve a device which has a low characteristicimpedance with low dependence on frequencies over a wide frequencyrange.

$\begin{matrix}{{Zy} = {\sqrt{\frac{R + {j\;\omega\; L}}{G + {j\;\omega\; C}}} \approx \sqrt{\frac{L}{C}}}} & (1)\end{matrix}$

The characteristic (2) will be examined below. As shown in FIG. 36, theimpedance of the line device can be evaluated by a circuit having aconstant characteristic impedance of Z0. As shown in FIG. 36, thecharacteristic of the line device is indicated by a transmissionproperty from a port 1 to a port 2. A reflection coefficient F and atransmission coefficient T for evaluating the circuit are factors S11and S21 of a scattering matrix [S] and are expressed by the formulabelow:

$\begin{matrix}{{\lbrack S\rbrack = {\frac{1}{{2{\hat{Z}}_{y}} + 1}\begin{bmatrix}{- 1} & {2{\hat{Z}}_{y}} \\{2{\hat{Z}}_{y}} & {- 1}\end{bmatrix}}}{{where},{{\hat{Z}}_{y} = \frac{Z_{y}}{Z_{0}}}}} & (2)\end{matrix}$where Z0 represents a characteristic impedance of an input/output lineof the line device and Zy represents an impedance of the line device.Therefore, in the case of Z0>>Zy, Γ≈−1 and T≈0 are established and ahigh frequency electromagnetic wave to be inputted can be reflectedaround the entrance of the transmission line.

As described above, the characteristic impedance of the line iscalculated by (L/C)^(1/2) and thus is determined only by a capacitancecomponent and an inductance component. Since the characteristicimpedance has a constant value relative to a frequency, the decouplingproperty is not theoretically degraded by a frequency.

FIG. 37 shows the factor S21 (see Formula (4)) of the sequence [S]indicating the transmission coefficient T of a decoupling device. Inother words, FIG. 37 is a diagram showing the relationship between afrequency and a transmittance of the decoupling device. In FIG. 37, abroken line indicates a transmission coefficient when a capacitor isconnected to a line of a power distribution circuit and is caused to actas a decoupling device. A solid line indicates a transmissioncoefficient when a line of the power distribution circuit is caused tohave a wiring capacitance and act as a decoupling device. The verticalaxis represents a transmittance (dB) and the horizontal axis representsa frequency (GHz).

When a comparison is made between a transmittance when the capacitor isconnected to the line of the power distribution circuit and atransmission when the line of the power distribution circuit is causedto have a wiring capacitance, a transmission is smaller when the line iscaused to have a wiring capacitance (that is, a cutting rate is high),thereby achieving an excellent decoupling property.

In this way, unlike the decoupling of the power distribution circuitthat is conventionally performed using a capacitor, decoupling can beperformed by providing a line structure and inserting a device in whichan L (inductance), a C (capacitance), and an R (resistance) are set atproper values and a line has a decoupling property.

Parameters for obtaining a desired decoupling property include L, C, andR. When L and R increase, a problem occurs which includes greatfluctuations in power supply voltage during the switching of a logiccircuit. Thus, it is necessary to adjust the decoupling property byadjusting C.

The following will describe a configuration when the stripline devicesof the first to thirteenth embodiments are mounted on a semiconductorpackage.

As shown in FIG. 38, the stripline device and a semiconductor chip 403are arranged on a substrate 405 made of an insulating material. Thestripline devices of the first to thirteenth embodiments are disposedbetween a power supply wire 401 b and a ground wire 402 b of thesemiconductor chip and a power supply wire 401 a and a ground wire 402 aof connector pins provided on the substrate 405. The power supply wire401 b of the semiconductor chip and the power supply wire 401 a of theconnector pin are connected to the anode leading terminals 11 and 12 ofthe stripline device. The ground wire 402 b of the semiconductor chipand the ground wire 402 a of the connector pin are connected to thecathode leading terminals 41 and 42 of the stripline device.

High frequency noise from the semiconductor chip 403 mounted on thesubstrate 405 is superimposed on the power supply wire 401 b and theground wire 402 b, propagates through these wires, and causes circuitelements to malfunction. By filtering the noise in the stripline deviceincluded in the semiconductor package, a malfunction caused by highfrequency noise is less likely to occur on a semiconductor device ofFIG. 38, thereby achieving stable circuit operations at highfrequencies. The above explanation described that a wire paired with thepower supply wire is the ground wire. A negative power supply wire maybe paired with the power supply wire.

The above-described embodiments are preferred embodiments of the presentinvention. The embodiments are not limited to the above and variouschanges can be made within the scope of the present invention.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, a striplinedevice is constituted of a valve metal having a dielectric coating, aconductive material layer disposed around the valve metal via thedielectric coating, a pair of electrode leading terminals disposed ondifferent positions of the valve metal, and a pair of electrode leadingterminals disposed on different positions of the conductive materiallayer. This configuration increases an apparent dielectric loss and thusthe characteristic impedance of the stripline device can be sufficientlyreduced, thereby preventing an electromagnetic wave generated from anoise source from entering a power distribution circuit.

Further, when a long metal with a length larger than a cross sectionaldimension by four times or more is used as the valve metal, a noisereduction effect can be exerted more effectively.

Moreover, both ends of the valve metal are bent or curved in onedirection. Thus, only by dipping into a solution for anodization or asolution for forming a layer of a conductive material, it is possible toreadily manufacture the stripline device and readily obtain a shape forperforming packaging while avoiding other components.

A substrate and the stripline devices are positioned and bonded to eachother such that the conductive material layers and metal members are incontact with each other and lead frames and the valve metals are incontact with each other. On the substrate, the plurality of metalmembers having first electrode leading terminals and the plurality oflead frames serving as second electrode leading terminals are integrallyformed, and the stripline devices are obtained in a process before theformation of the conductive material layers. The first electrode leadingterminals and the lead frames are cut from the substrate at apredetermined distance, so that the stripline device is obtained. Thesesteps make it possible to readily manufacture the stripline device of afour-terminal structure.

1. A stripline device, comprising: a metal having a valve action; adielectric coating formed on a surface of the metal having the valveaction; a conductive material layer formed around the metal having thevalve action via the dielectric coating; a metal member attached to theconductive material layer; a pair of first electrode leading terminalsprovided on both ends in a longitudinal direction of the metal havingthe valve action to make connection to through holes of a printed wiringboard; and a pair of second electrode leading terminals provided ondifferent positions of the metal member to make connection to thethrough holes of the printed wiring board.
 2. The stripline deviceaccording to claim 1, wherein the metal having the valve action isrectangular in cross section.
 3. The stripline device according to claim1, wherein the metal having the valve action is circular or oval incross section.
 4. The stripline device according to claim 1, wherein themetal having the valve action is shaped like a ring in cross section. 5.The stripline device according to claim 1, wherein the metal having thevalve action is formed into a plate or foil.
 6. The stripline deviceaccording to claim 1, wherein both ends of the stripline device are bentor curved.
 7. The stripline device according to claim 1, wherein themetal having the valve action has a longitudinal width larger than across sectional width.
 8. The stripline device according to claim 1,wherein one of the first and second electrode leading terminals incontact with the printed wiring board has an area larger than across-sectional area of the another of the first and second electrodeleading terminals not coming into contact with the printed wiring board.9. The stripline device according to claim 1, wherein the conductivematerial layer includes a layer of a conducting polymer.
 10. Thestripline device according to claim 9, wherein the conducting polymer isone or more compounds selected from the group consisting of polypyrrole,polythiophene, and polyaniline, or a derivative of the compounds. 11.The stripline device according to claim 9, wherein the conductivematerial layer has the conducting polymer layer disposed on a side ofthe dielectric coating and a conductive paste layer formed on theconducting polymer layer.
 12. The stripline device according to claim11, wherein the metal member is fixed on the conductive paste layer. 13.The stripline device according to claim 1, wherein the metal having thevalve action is a metal selected from the group consisting of aluminum,tantalum, and niobium.
 14. The stripline device according to claim 1,wherein the metal having the valve action, the dielectric coating, andthe conductive material layer are molded with resin.
 15. A striplinedevice, comprising: a metal having a valve action, a dielectric coatingformed on a surface of the metal, a conductive material layer formedaround the metal via the dielectric coating, and a metal member which isdisposed in contact with the conductive material layer and transmitsdirect-current power, wherein: the stripline device includes a firstelectrode leading terminals for connecting an end of the metal havingthe valve action and a printed wiring board; second electrode leadingterminals connected to the printed wiring board are integrally formed onthe metal member; and the second electrode leading terminals and thefirst electrode leading terminals connected to both ends of the metalhaving the valve action form four terminals.
 16. The stripline deviceaccording to claim 15, wherein: the first electrode leading terminalincludes: a connecting member connected to the metal having the valveaction; a first leg member connected to a wire on the printed wiringboard; and a first body member for connecting the connecting member andthe leg member; the connecting member and the first leg member areconnected almost perpendicularly to both ends in a longitudinaldirection of the first body member; each second electrode leadingterminal integrally formed on the metal member includes: a second bodymember; and a second leg member for making connection to another wire onthe printed wiring board; the second body member is connected to anupper end of a mounting surface of both ends in a longitudinal directionof the metal member; and the second leg member is connected to the bodymember almost in parallel with the mounting surface.
 17. The striplinedevice according to any one of claim 16, wherein the first leg memberand the second leg member have a cross sectional area larger than across sectional area of the first body member and the second body membernot coming into contact with the printed wiring board.
 18. The striplinedevice according to claim 15, wherein: the first electrode leadingterminal includes: a connecting member connected to the metal having thevalve action; a first leg member connected to a wire on the printedwiring board; and a first body member for connecting the connectingmember and the leg member; a member is provided to interpose the firstbody member between the connecting member connected to the first bodymember and the first leg member on both ends in a longitudinal directionof the first body member and connect the connecting member and the firstleg member almost perpendicularly to the first body member; and thesecond electrode leading terminals include second leg members connectedto both ends in a longitudinal direction of the metal member and nearone of long sides of the metal member almost in parallel with themounting surface.
 19. The stripline device according to claim 15,wherein: the first electrode leading terminal includes: a connectingmember connected to the metal having the valve action; and a first bodymember connected to a wire on the printed wiring board; the connectingmember is connected to an end in a longitudinal direction of the firstbody member almost perpendicularly to the first body member; and eachsecond electrode leading terminal includes a second body memberconnected almost perpendicularly to a vicinity of one of long sides ofboth ends in a longitudinal direction of the metal member.
 20. Thestripline device according to claim 15, wherein: the first electrodeleading terminal includes: a connecting member connected to the metalhaving the valve action; and a first body member connected to a wire onthe printed wiring board; the connecting member is connected to an endin a longitudinal direction of the first body member almostperpendicularly to the first body member; each second electrode leadingterminal includes a second body member connected almost perpendicularlyto a central area near both ends in a longitudinal direction of amounting surface of the metal member; and the first electrode leadingterminal and the second electrode leading terminal are disposed almostin line with each other in the longitudinal direction of the mountingsurface of the metal member.
 21. A method of forming a stripline device,comprising the steps of: forming a metal having a valve action; forminga dielectric coating on a surface of the metal having the valve action;forming a conductive material layer around the metal having the valveaction via the dielectric coating to form a strip line; bonding thestrip line and a plurality of substrates, on which a metal member havinga second electrode leading terminal and a lead frame serving as a firstelectrode leading terminal are integrally formed, after performingpositioning such that the conductive material layer and the metal memberare in contact with each other and the lead frame and the metal havingthe valve action are in contact with each other; and cutting the secondelectrode leading terminal and the lead frame from the substrate at apredetermined distance to complete a stripline device.